json转换工具类

我不是女神ヾ 2022-03-11 08:26 314阅读 0赞

import java.io.BufferedReader;
    import java.io.IOException;
    import java.io.InputStream;
    import java.io.InputStreamReader;
    import java.net.URL;
    import java.util.ArrayList;
    import java.util.HashMap;
    import java.util.Iterator;
    import java.util.List;
    import java.util.Map;
    import java.util.Set;
    
    import javax.servlet.http.HttpServletResponse;
    
    import org.slf4j.Logger;
    import org.slf4j.LoggerFactory;
    
    import com.fasterxml.jackson.databind.ObjectMapper;
    
    import net.sf.json.JSONArray;
    import net.sf.json.JSONObject;
    
    /**
    * @author leon
    * @createDate 2018年5月14日 下午3:21:06
    * @version v1.0
    * @classRemarks json工具类
    */
    public class JsonUtils {
    
    	private static final ObjectMapper objectMapper = new ObjectMapper();
    	/*** 编码 */
    	private static final String CHAR_ENCODING = "UTF-8";
    
    	private static Logger logger = LoggerFactory.getLogger(JsonUtils.class);
    
    	/**
    	 * 将 Java 对象转为 JSON 字符串
    	 */
    	public static String obj2JSON(Object obj) {
    		String jsonStr;
    		try {
    			jsonStr = objectMapper.writeValueAsString(obj);
    		} catch (Exception e) {
    			logger.error("Java 转 JSON 出错！", e);
    			throw new RuntimeException(e);
    		}
    		return jsonStr;
    	}
    
    	/**
    	 * 将 JSON 字符串转为 Java 对象
    	 */
    	@SuppressWarnings({ "rawtypes", "unchecked" })
    	public static <T> T json2Object(String json, Class type) {
    		T obj;
    		try {
    			obj = (T) objectMapper.readValue(json, type);
    		} catch (Exception e) {
    			logger.error("JSON 转 Java 出错！", e);
    			throw new RuntimeException(e);
    		}
    		return obj;
    	}
    
    	/**
    	 * json串 转map
    	 * 
    	 * @param jsonStr
    	 * @return
    	 */
    	public static Map<String, Object> parseJSON2Map(String jsonStr) {
    		Map<String, Object> map = new HashMap<String, Object>();
    		JSONObject json = JSONObject.fromObject(jsonStr);
    		for (Object k : json.keySet()) {
    			Object v = json.get(k);
    			if (v instanceof JSONArray) {
    				List<Map<String, Object>> list = new ArrayList<Map<String, Object>>();
    				Iterator<JSONObject> it = ((JSONArray) v).iterator();
    				while (it.hasNext()) {
    					JSONObject json2 = it.next();
    					list.add(parseJSON2Map(json2.toString()));
    				}
    				map.put(k.toString(), list);
    			} else {
    				map.put(k.toString(), v);
    			}
    		}
    		return map;
    	}
    	
    	/**
    	 * Json转map和List<Map<String,Object>>
    	 * 
    	 * @param jsonStr
    	 * @return
    	 * @throws Exception
    	 */
    	@SuppressWarnings("unchecked")
    	public static List<Map<String, Object>> parseJSON2Listmap(String jsonStr) {
    		// Gson gson = new Gson();
    		ObjectMapper objectMapper = new ObjectMapper();
    		List<Map<String, Object>> newMap = null;
    		try {
    			newMap = objectMapper.readValue(jsonStr, List.class);
    		} catch (Exception e) {
    			logger.error("系统错误:",e);
    		}
    		//System.out.println(newMap);
    		return newMap;
    	}
    
    	/**
    	 *
    	 * 通过HTTP获取JSON数据. <br>
    	 * 通过HTTP获取JSON数据返回list
    	 * 
    	 * @param url
    	 *            链接
    	 * @return
    	 * @return List<Map<String,Object>> list
    	 * @throws @author
    	 *             slj
    	 */
    	public static List<Map<String, Object>> getListByUrl(String url) {
    		try {
    			// 通过HTTP获取JSON数据
    			InputStream in = new URL(url).openStream();
    			BufferedReader reader = new BufferedReader(new InputStreamReader(in));
    			StringBuilder sb = new StringBuilder();
    			String line;
    			while ((line = reader.readLine()) != null) {
    				sb.append(line);
    			}
    			return parseJSON2Listmap(sb.toString());
    		} catch (Exception e) {
    			logger.error("系统错误:",e);
    		}
    		return null;
    	}
    
    	/**
    	 *
    	 * 通过HTTP获取JSON数据. <br>
    	 * 通过HTTP获取JSON数据返回map
    	 * 
    	 * @param url
    	 *            链接
    	 * @return
    	 * @return Map<String,Object> 集合
    	 * @throws @author
    	 *             slj
    	 */
    	public static Map<String, Object> getMapByUrl(String url) {
    		try {
    			// 通过HTTP获取JSON数据
    			InputStream in = new URL(url).openStream();
    			BufferedReader reader = new BufferedReader(new InputStreamReader(in));
    			StringBuilder sb = new StringBuilder();
    			String line;
    			while ((line = reader.readLine()) != null) {
    				sb.append(line);
    			}
    			return parseJSON2Map(sb.toString());
    		} catch (Exception e) {
    			logger.error("系统错误:",e);
    		}
    		return null;
    	}
    
    	/**
    	 *
    	 * map转换json.
    	 * @param map 集合
    	 * @return
    	 */
    	public static String mapToJson(Map<String, String> map) {
    		Set<String> keys = map.keySet();
    		String key = "";
    		String value = "";
    		StringBuffer jsonBuffer = new StringBuffer();
    		jsonBuffer.append("{");
    		for (Iterator<String> it = keys.iterator(); it.hasNext();) {
    			key = (String) it.next();
    			value = map.get(key);
    			jsonBuffer.append(key + ":" + "\"" + value + "\"");
    			if (it.hasNext()) {
    				jsonBuffer.append(",");
    			}
    		}
    		jsonBuffer.append("}");
    		return jsonBuffer.toString();
    	}
    	
    	/**
    	 * 返回json格式的数据
    	 * 
    	 * @param response
    	 * @param jsonObject
    	 */
    	public static void doJsonResponse(HttpServletResponse response,
    			final JSONObject jsonObject) {
    		response.setCharacterEncoding(CHAR_ENCODING);
    		response.setContentType("application/json; charset=utf-8");  
    		try {
    			response.getWriter().print(jsonObject);
    		} catch (IOException e) {
    			logger.error(e.getMessage());
    			logger.error("系统错误:",e);
    		}
    	}
    
    }